Thermo-electric refrigerators



May 30, 1961 J. J. GAYsowsKl 2,986,009

THERMO-ELECTRIC REFRIGERATORS Filed July 13, 1959 3 sheets-sheet 1 J. J. GAYSOWSKI THERMO-ELECTRIC REFRIGERATORS Filed July 13, 1959 3 Sheets-Sheet 2 5/ Fzg 3 26" x 45" n50 cou/LES M ffm-5r M I @l I 9a J/02 lOl-f- I 90- {e- I I I f95 I P4/ 96 /5"x 36" I @00L 88 76 I 555 G01/m55 I I 7 0 74 I@ n2, I I l X350 I 75 e) I 3/5 COUPLES 825 75 I 54 SAT mmf I TE I n" 64 .y 9?

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May 30, 1961 J. J. GAYsowsKl THERMO-ELECTRIC REFRIGERATORS 5 Sheets-Sheet 3 Filed July 13, 1959 IN VENTOR. Jnsep/l J. Gaysows/ri United States Patent O THERMO-ELECTRIC REFRIGERATDRS Joseph J. Gaysowski, Chicago, Ill., assignor to General Electric Company, a corporation of New York Filed July 13, 1959, Ser. No. 826,769

14 claims. (c1. 623) The present invention relates to thermo-electric refrigerators, and more particularly to an improved thermoelectric pile for use in such refrigerators and related appliances,

It is a general object of the invention to provide a refrigerator incorporating a thermo-electric pile for the cooling purpose, together with an improved circuit arrangement for selectively controlling the thermo-electric pile.

Another object of the invention is to provide in a refrigerator, or related appliance, an improved arrangement of a thermo-electric pile, so as to cause a Peltier effect as required in thetransfer of heat between the appliance and the ambient air.

A further object of the invention is to provide a refrigerator cabinet structure of improved construction and arrangement, including a plurality of storage chambers, a plurality of thermo-electric piles arranged to effect the cascading of heat through a series of the storage chambers.

A further object of the invention is to provide a thermo-electric pile of improved and simplified construction and arrangement that may be readily incorporated in a refrigerator cabinet, or related appliance, in order to govern the transfer of heat between the appliance and the ambient air.

Further features of the invention pertain to the particular arrangement of the elements of the refrigerator and of the elements of the thermo-electric pile, whereby the above-outlined and additional operating features thereof are attained.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification, taken in connection with the accompanying drawings, in which:

Figure l is a fragmentary vertical sectional view of a refrigerator of the household type incorporating a thermo-electric pile and embodying the present invention;

Fig. 2 is a front elevational view of the refrigerator shown in Fig. 1, with the front door removed from the adjacent cabinet section thereof;

Fig. 3 is a combination schematic illustration of the arrangement of the thermo-electric piles incorporated in the refrigerator of Figs. 1 and 2, and a Wiring diagram of the electric circuit control system therefor;

Fig. 4 is an enlarged fragmentary plan view of one of the thermo-electric piles incorporated in the refrigerator of Figs. 1 and 2; and

Fig. 5 is an enlarged vertical sectional view of the thermo-electric pile, taken in the direction of the arrows along the line 55 in Fig. 4.

Referring now to Figs. 1 and 2, the refrigerator 10 there illustrated and embodying the features of the present invention is of the household type including an upstanding heat-insulating cabinet section 21 provided with both an open top and an open front, and an associated heat-insulating front door section 31. Also, the refrig- ICC erator 10 is provided with a supporting base 41 providing an apparatus compartment 42 in which certain apparatus, described more fully hereinafter, is housed. More particularly, the cabinet section 21 includes a rear wall 22, a bottom Wall 23 and a pair of side walls 24 and 25; the open top of the cabinet section 21 is closed by a top wall or panel P5; and the interior of the cabinet section 21 is divided into five food storage chambers C1 to C5, inclusive, by four panels P1 to P4, inclusive, arranged in vertically spaced-apart relation between the bottom Wall 22 and the top wall or panel P5; whereby the chambers C1 to C5, inclusive, are arranged in a tier.

As clearly illustrated in Fig. 2, the panel P1 comprises a thermo-electric pile dividing the chamber C1 from the chamber C2 and adapted to maintain the temperature of the chamber C1 in the general range 0 to 10 F. and to maintain the temperature of the chamber C2 in the general range 10 to 20 F. The panel P2 comprises a thermo-electric pile dividing the chamber C2 from the chamber C3 and adapted rto maintain the temperature of the chamber C2 in the previously mentioned general range 10 to 20 F. and to maintain the temperature of the chamber C3 in the general range 20 to 30 F. The panel P3 comprises a thermo-electric pile dividing the chamber C3 from the chamber C4 and adapted to maintain the temperature of the chamber C3 in the previously mentioned general range 20 to 30 F. and to maintain the temperature of the chamber C4 in the general range 30 to 40 F. The panel P4 cornprises a thermo-electric pile dividing the chamber C4 from the chamber C5 and adapted to maintain the temperature of the chamber C4 in the previously mentioned general range 30 to 40 F. and to maintain the temperature of the chamber C5 in the general range 40 to 60 F. The panel P5 comprises a thermo-electric pile separating the chamber C5 from the ambient air and adapted to maintain the temperature of the chamber C5 in the previously mentioned general range 40 to 60 F., when the ambient air has a temperature of 70 F.

Moreover, each of the piles P1 to P5, inclusive, includes a plurality of thermocouples, each including a hot junction and a cold junction. In the pile P1, the cold junctions are arranged in heat exchange relation with the air in the top of the chamber C1, and the hot junctions are arranged in heat exchange relation with the air in the bottom of the chamber C2. In the pile P2, the cold junctions are arranged in heat exchange relation with the air in the top of the chamber C2 and the hot junctions are arranged in heat exchange relation with the air in the bottom of the chamber C3. In the pile P3, the cold junctions are arranged in heat exchange relation with the air in the top of the chamber C3, and the hot junctions are arranged in heat exchange relation with the air in the bottom of the chamber C4. In the pile P4, the cold junctions are arranged in heat exchange relation with the air in the top of the chamber C4 and the hot junctions are arranged in heat exchange relation with the air in the bottom of the chamber C5. In the pile P5, the cold junctions are arranged in heat exchange relation with the air in the top of the chamber C5 and the hot junctions are arranged in heat exchange relation wtih the ambient air exteriorly of the cabinet section 21 and adjacent to the top thereof.

In the refrigerator 10, a plurality of lower screens of foraminous construction LS1 to LS5, inclusive, are respectively arranged below and adjacent to the piles P1 to P5, inclusive, for the fundamental purpose of preventing short-circuiting of the thermocouples incorporated therein; and likewise, a plurality of upper screens of foraminous construction USI to US5, inclusive, are respectively arranged above and adjacent to the piles P1 to PS,. inelusive, for the fundamental purpose of preventing short circuiting of the thermocouples incorporated therein. The screens LS1, etc., and US1, etc., prevent the shortcircuiting of the thermocouples incorporated in the respective piles P1, etc., without, in any way, interfering with the ready conduction of heat, by convection currents, with respect to the associated piles P1, etc.; and moreover, the upper screens USI, US2, USS and U84 serve the additional purpose of food-supporting shelves in the respective food storage chambers C2, C3, C4 and C5.

As generally illustrated in Fig. 2, the refrigerator l comprises electrical apparatus 50 housed in the base 4l and supplied with A.C. power of 118 volts, single-phase; which apparatus 50 supplies direct current in parallel circuit relation to the piles P1 to P5, inclusive. Also, the refrigerator 10 comprises a temperature-responsive device T arranged in the side wall 25 of the cabinet section 21 and subject to the temperature of the storage air in the chamber C3; which temperature-responsive device T preferably takes the form of a thermistor. Also, in the arrangement, the thermistor T is employed for the purpose of selectively controlling the electrical apparatus 50, as explained more fully hereinafter.

Referring now to Fig. 3, in a construction example of the refrigerator 10: the pile P1 comprises 66 thermocouples and occupies an `area of approximately 6" x 11; the pile P2 comprises 168 thermocouples and occupies an area of approximately 7" x 24; the pile P3 comprises 316 thermocouples and occupies an area of approximately 1l x 30; the pile P4 comprises 536 thermocouples and occupies an area of approximately 15" x 36; and the pile S comprises 1150 thermocouples and occupies an area of approximately 26 x 45". As explained more fully hereinafter, each of the piles P1, etc., is arranged substantially centrally with respect to the associated partition and each of the partitions is about 27 x 48". In the arrangement: the distance between the rear wall 22 of the cabinet section 21 and the front door 3l in its closed position is approximately 27"; the distance between the side walls 24 and 25 of the cabinet section 21 is approximately 48; the lowermost partition P1 is spaced above the bottom wall 22 a distance approximately 12"; and the adjacent partitions P1, P2, etc., are separated from each other by distances of approximately l2". Accordingly, each of the chambers C1, C2, etc., has a volume approximately l2 x 27 x 48".

As illustrated in Fig. 3, the apparatus 50 essentially comprises a plug 51 that is insertible into an associated socket, not shown, terminating the previously mentioned A.C. supply source, and a cable 52 connected to the plug 51 and including a pair of conductors 53 and 54, the conductors 53 and 54 being terminated by a switch 55 of the double-pole single-throw type. Further, the apparatus 50 comprises a power transformer 60 including a primary winding 61 and a secondary winding 62, a control transformer 701 including a primary winding 71 and a secondary winding 72, and a magnetic amplifier 80 including a saturable magnetic core 81 provided with an exciting winding 82 and a reactive winding 83. The two output terminals of the power switch 55 are respectively connected to two conductors 56 and 57; the primary winding 71 is bridge across the conductors 56 and 57; and the primary winding 61 is connected in series relation with the reactive winding 83 and bridged across the conductors 56 and 57. The secondary winding 62 is provided with a `center tap that is connected to a negative bus 63; and the extremities of the secondary winding 62 are respectively connected by a pair of diode rectiliers 64 and 65 to a positive bus 66, a filtering capacitor 67 being bridged across the negative and positive buses 63 and 66. The secondary winding 72 is provided with a center tap that is connected to a negative bus 73; and the extremities of the secondary winding 72 are respectively connected by a pair of diode rectiers 74 and 75 to a positive bus 76, a filtering capacitor 77 being bridged across the negative and positive buses 7'3 and 74.

The apparatus 50 further comprises a control switch provided with a cool position and a defrost position; which switch 90 comprises three movable switch blades 91, 92 and 93, three stationary front switch blades 94, 95 and 96 and two stationary back switch blades 97 and 98. When the control switch 90 occupies its cool position, the movable switch blades 91, 92 and 93 respectively engage the front switch blades 94, 95 and 96; and when the control switch 90 occupies its defrost position, the movable switch blades 91 and 92 respectively engage the back switch blades 97 and 98. The negative bus 73 is connected to one terminal of the exciting winding 82; and other terminal of the exciting winding 82 is connected by a conductor 84 to a contact 85 that is operatively associated with a variable resistor 86 that, in turn, terminates a conductor 87. The thermistor T is bridge dacross the conductor 87 and a conductor 88. ln the switch 90: the blades 91, 92 and 93 respectively terminate the conductors 63, 66 and 76; the blades 94 and 98 commonly terminate a power supply bus 101; the blades 95 and 97 commonly terminate a power supply bus 102; and the blade 96 terminates the conductor 88.

Considering now the general mode of the operation of the refrigerator 10, and assuming that the plug 51 is inserted into the associated A.C. power supply source, that the power switch 55 occupies its closed position, and that the control switch 90 controls its cool position; the primary winding 71 is energized effecting energization of the secondary winding 72, with the result that a D.-C. voltage appears between the conductors 73 and 76, effecting energization of the exciting Winding 82 in series circuit relation with the resistor 86 and the thermistor T, the circuit including the closed switch blades 93 and 96, as well as the conductors 87, 88 and 84. At this time, it may be assumed that the chamber C3 in the refrigerator 10 is hot so that the thermistor T has a relatively low resistance, thereby to cause a direct exciting current to traverse the exciting winding 82 that is adequate to cause saturation of the magnetic core 81 of the magnetic amplier 80, with the result that the reactive winding 83 has very small impedance. Accordingly, a substantial primary current traverses the primary winding 61 in series circuit relation with the reactive winding 83 inducing a substantial voltage in the secondary winding 62, with the result that a substantial D.C. voltage appears between the buses 63 and 66; the bus 63 is connected via the switch blades 91 and 94 to the supply conductor 101 impressing a negative potential thereupon; and the bus 66 is connected via the switch blades 92 and 95 to the supply conductor 102 impressing a positive potential thereupon. Accordingly, the five thermo-electric piles P1 to P5, inclusive, are energized in parallel circuit relationship 'between the supply conductors 101 and 102` and the polarity is such that the lower junctions thereof comprises cold junctions and upper junctions thereof comprises hot junctions; whereby the chambers C1 to C5, inclusive, are progressively cooled due to the Peltier effects respectively produced by the piles P1 to P5, inclusive. Specifically, the heat from the chamber C1 is cascaded into the chamber C2 by the pile P1; the heat from the chamber C2 is cascaded into the chamber C3 by the pile P2; the heat from the chamber C3 is cascaded into the chamber C4 by the pile P3; the heat from the chamber C4 is cascaded into the chamber C5 by the pile P4; and the heat from the chamber C5 is cascaded into the ambient air by the pile P5.

As the cooling operation of the apparatus 50 continues, the temperature in the chamber C3 is lowered, so that the resistance of the thermistor T is correspondingly increased, thereby to increase the resistance of the circuit including the exciting winding 82, with the result that the current traversing the exciting winding 82 is progressively decreased, so as to bring about progressively reduced amounts of saturation of the magnetic core 81 of the magnetic amplifier 80; whereby the impedance of the reactive winding 83 is correspondingly and progressively increased. As the impedance of the reactive winding 83 is progressively increased, the voltage impressed across the primary winding 61 is progressively reduced, with the result that the D.-C. voltage impressed across the buses 63 and 66 is progressively reduced, causing a corresponding reduction in the voltage impressed across the supply conductors 101 and 102; whereby the currents respectively traversing the piles P1 to P5, inclusive, are correspondingly reduced, so as correspondingly to reduce the cooling elects upon the chambers C1 to C5, inclusive. Accordingly, it will be understood that as the temperature of the chamber C4 is reduced, the resistance of the thermistor T is increased, with the result that the impedance of the reactive winding 83 is increased, with the result that the Voltage impressed between the supply conductors 101 and 102 is reduced, thereby reducing the Peltier effect produced by the piles P1 to P5, inclusive; whereby the thermistor T controls the apparatus 50 to establish the rate of heat transfer by the piles P1 to P5, inclusive, from the refrigerator 10 to the ambient air.

ln the arrangement, the piles P1 to P5, inclusive, progressively include larger numbers of thermocouples, as previously explained, so that the piles P1 to P5, inclusive, are capable of transferring progressively larger amounts of heat; whereby ultimately the temperatures of the chambers C1 to C5, inclusive, may be brought respectively into the previously mentioned temperature ranges, progressively decreasing below the ambient temperature in the downward direction in the tier.

Further, it will be understood that by adjustment of the contact 85 relative to the variable resistor 86, a higher temperature or a lower temperature may be maintained in the refrigerator 10, the temperature maintained being lowered as the resistance of the resistor 86 is decreased, and the temperature maintained being raised as the resistance of the resistor 86 is increased. This effect will be readily appreciated when it is observed that the inclusion of additional resistance of the resistor 86 in the circuit of the exciting Winding 82 reduces the exciting current` thereby to bring about an increase in the impedance of the reactive winding 83.

Of course, -it will be understood that the effects produced by the thermistor T and the manually adjustable contact 85 cooperating with the variable resistor 86 are substantially amplified by the magnetic amplifier 80 by virtue of the usual magnetic amplification factor of the magnetic amplier 80, as is well-understood.

In order to effect defrosting of the refrigerator 10, it is only necessary to reverse the position of the control switch 90; whereby the switch blades 91, 92 and 93 disengage the front switch blades '94, 95 and 96, and the switch blades 91 and 92 respectively engage the back switch blades 97 and 98. This reversal of the control switch 90 reverses the polarity that is applied to the supply conductors 101 and 102; whereby the Peltier effects produced in the piles P1 to P5, inclusive, are reversed, with the result that heat is pumped from the arnbient air into the chamber C5 by the pile P5; which heat is cascaded by the piles P4, P3, P2 and P1, respectively, through the chambers C5, C4, C3, C2 and C1. More particularly, the reversal of polarity as applied to the supply conductors 101 and 102 brings about the reversal of the normal hot junctions and the normal cold junctions of the thermocouples in each of the piles P1, etc.; whereby the heat is pumped from the exterior or ambient air into the refrigerator in the manner described above.

Considering now the construction and arrangement of each of the thermo-electric piles P1 to P5, inclusive, these piles are preferably of the same basic construction, but include a progressively increasing number of thermocouples, as previously explained.

Referring now to Figs. 4 and 5, the thermo-electric pile there illustrated may be assumed to be the pile P3; and the composite partition provided in the cabinet section 21 between the chambers C3 and C4 comprises a stationary section 111 and a movable section 112, the stationary section 111 constituting a flat sheet having the previously mentioned dimensions 27" x 48 and having a centrally disposed opening 113 therein into which the movable section 112 is arranged, the opening 113 having the previously mentioned dimensions 11" X 30". The movable section 112 also carries the previously described lower and upper screen respectively indicated at LS3 and U83, the screens LS3 and US3 being of foraminous construction, as previously noted.

Provided through the plate 112 are a number of substantially cylindrical holes that are arranged in a substantially uniform geometric pattern; in odd ones of these holes, there are arranged N-type semi-conductors 114; and in even ones of these holes, there are arranged P-type semi-conductors 115. A rst group of metallic conductors 121 are arranged upon the lower side of the plate 112, and a second group of metallic conductors 122 are arranged upon the upper side of the plate 112; which metallic conductors 121 and 122 :are substantially identical. In ythe arrangement, each of the conductors 121 and 122 includes a central bridging strap and a pair of outwardly projecting heat-exchange tins formed integrally therewith. A pair of holes are formed in each of the strap portions in each of the conductors 121 and 122; and electrical connections are formed through the holes mentioned with the adjacent ends of the semi-conductors 114 and 115, as, for example, by soldering, as indicated at 123. Accordingly, the lower group of conductors 121 respectively connect together the adjacent ends of the P-N types of semi-conductors 11S-114; and the upper group of conductors 122 respectively connect together the adjacent ends of the N-P types of semi-conductors 114- 115; whereby all of the N-type semi-conductors and all the P-type semi-conductors 115 and all of the metallic conductors 121 and 122 are connected in series circuit relationship. As best illustrated in Fig. 5, it will be observed that a rst of the conductors 121 is connected via a rst of the N-type `semi-conductors 114 to a first of the conductors 122; this first conductor 122 is connected via a rst of the P-type semi-conductors 115 to a second of the conductors 121; lthis second conductor 121 is connected via a second of the N-type semi-conductors 114 to a second of the conductors 122; etc. Accordingly, in the arrangement, when a relatively positive potential is connected to the left-hand conductor 121 and a relatively negative potential is connected to the righthand conductor 122, all of the junctions between the semi-conductors 114 and 115 and the conductors 121 comprise cold junctions of the corresponding thermocouples and all of the junctions between the semi-conductors 114 and 115 and the conductors 122 comprise hot junctions of the corresponding thermocouples. Hence, in the pile P3, all of the cold junctions are disposed in heat-exchange relation with the ns of the conductors 121 disposed in the top of the chamber C3 and all of the hot junctions are disposed in heat-exchange relation with the iins of the conductors 122 disposed in the bottom of the chamber C4; with the result that the tins of the conductors 12-1 absorb heat in the chamber C3 and transfer this heat through the plate 112 (through the semiconductors 114 and 115) to the conductors 122; and the fins of -the conductors 122 deliver this heat into the chamber C4.

Considering now in greater detail the constructional example of the thermo-electric pile P3, each of the semiconductors 114 is formed essentially of Bi2'1`e3 and contains a small controlled amount of a donor impurity to render the same an N-type semi-conductor; and each of the semi-conductors 115 is formed essentially of BigTea and contains a small controlled amount of an acceptor impurity to render the same a P-type semi-conductor. Ordinarily, the donor impurity contained in an N-type semi-conductor is selected from the group consisting of P, As and Sb; and ordinarily, the acceptor impurity contained in a P-type semi-conductor is selected from the group consisting7 of B, Al, Ga and In. Each of the N- type semi-conductors 114 is of cylindrical form having a diameter of about %4 (with a cross-sectional area of 1.0 o2); and each of the P-type semi-conductors 115 is of cylindrical form having a diameter of about 5/32" (with a cross-sectional area of 1.1 cm.2). Each of the cylinders 114 and 115 has a length of 1 cm.

The plates or panels 111 and 112 comprise at sheets and are formed of plastic or ceramic heat-insulating and electrical-insulating material; and preferably, the panel 112 is formed of a phenolformaldehyde condensation product, a melamine resin or a high-density polyethylene, and has a thickness of approximately 1 cm. substantially to match the length of the cylinders 114 and 115. In the arrangement, the material of the panel 112 may be cast in place about the cylinders 114 and 115, or alternatively suitable holes may be first provided through the panel 112 and the cylinders 114 and 115 may be located in the holes and suitably cemented in place therein. Accordingly, the plate 112 also has a thickness of about 1 cm. and the holes formed therein are arranged in a grid-pattern with a space therebetween of about 1 in each of the X and Y directions.

Each of the metallic conductors 121-122 may be formed of copper, or other suitable metal that is both a good thermal conductor and a good electrical conductor. Each of the conductors 121 and 122' may be formed of ribbon stock 5%, wide and j,/16" thick. The strap section of each of the conductors mentioned may be approximately 11/2 long and each of the iin sections thereof may be approximately 1/2 long or high.

Further considering the thermocouples provided in the pile P3, the figure of merit of each thermocouple is 2.08)(*3 per C. (or higher); also, the resistance of each thermocouple is 0.0016 ohm (or less), and the thermal conductivity of each thermocouple is 0.0534 watt per C. per cm. (or less). Furthermore, the thermo-electric power of each of the semi-conductors 114- 115 exceeds 200 106 volt per C.

In the refrigerator 10, each of the panels P2, etc. is constructed to provide a cooling eect that is approximately 100 watts (or 341 Btu/hr.) greater than the total heat given off by the panel P1, etc., disposed therebelow. This arrangement allows each thermo-electric panel or pile P2, etc., to provide sufficient cooling effect for cooling any food, or the like, placed in the associated chamber C2, etc.; and each panel C2, etc., delivers heat at the top side thereof which is equivalent to the heat given off by the panel C1, etc., disposed therebeloW p-lus the D.C. power losses in the panel itself plus the heat removed from any food, or the like, stored in the chamber C2, etc., immediately therebelow.

The general performance of the refrigerator 10 is set forth in the two tables, appearing below:

TABLE II Average Average Cooling Average Heat per Power Output Panel Thermo- Input per per couple Tllernm- Thermo- (watts) couple couple (watts) (watts) P1 (bottom) 1A 50 0. 7B 2y 23 l 50 0. 73 2. 23 l 5l) 0, 73 2. 23 P4 l 50 0.73 2.23 P5 (top) 1 13 O. 90 2. 03

In the foregoing description of the connection and arrangement of the thermo-electric pile P3, it was explained that all of the semi-conductors 114 and 115 and all of the metallic conductors 121 and 122 are connected in series circuit relationship between the power supply conductors 101 and 102 in the refrigerator 10, and this is an entirely satisfactory arrangement with respect to the pile P3 that comprises only 316 thermocouples. However, in the pile P4 that comprises 536 thermocouples, the thermocouples may be arranged in two groups that are connected in parallel relationship with respect to each other; and similarly, in the pile P5 that comprises 1150 thermocouples, the thermocouples may bc arranged in four groups that are connected in parallel relationship with respect to each other. This connection of the thermocouples in appropriate series and parallel groups is dependent upon the total number of thermocouples included in the corresponding thermo-electric pile; and in each thermo-electric pile, the number of thermocouples that are connected in series circuit relationship with each other and thus across the power supply conductors 101 and 102 should be related to the number of thermocouples included in the various piles and selected so as to obtain the required current through the series connected thermocouples so as to produce the desired Peltier effects, as explained above, and as particularly pointed out in the foregoing Tables I and II.

The foregoing data relative to the general performance of the refrigerator 10 are predicated upon the incorporation therein of the thermo-electric piles of the general construction described in conjunction with Figs. 4 and 5, wherein the elements 114 and 115 respectively comprises N-type semi-conductors and P-type semi-conductors of the composition and arrangement set forth; however, the thermo-electric piles incorporated in the refrigerator 10 may be entirely conventional. For example, in a conventional thermo-electric pile of the general construction and arrangement, as shown in Figs. 4 and 5, the elements 114 are formed of metallic bismuth, the elements 115 are formed of metallic antimony and the conductors 121 and 122 are formed of copper. This conventional construction of the pile provides the required hot and cold junctions; however, the operating efficiency of this arrangement is not as high as that of the preferred arrangement, as previously described in conjunction with Figs. 4 and 5.

In view of the foregoing, it is apparent that there has been provided in a refrigerator of the household type an improved arrangement of a number of thermo-electric piles so as to obtain the required cascaded cooling in the several chambers disposed in the tier in the refrigerator cabinet. Also, there has been provided an improved thermo-electric pile and control circuit therefor of simpliiied connection and arrangement that -is suitable for incorporation in a refrigerator, or related appliance of the character described.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be understood that various modifications may be made therein, and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

What is claimed is:

l. In a refrigerator, upstanding hollow heat-insulating cabinet structure, a plurality of substantially horizontally disposed partitions arranged in said cabinet structure in substantially vertically spaced-apart relation and defining therein a plurality of chambers arranged in a tier, a plurality of thermoelectric piles respectively arranged in said partitions, each of said piles including a plurality of thermocouples each provided with a hot junction and a cold junction, the hot junctions of the thermocouples in each of said piles being arranged on the upper side of the associated partition and the cold junctions of the thermocouples in each of said piles being arranged on the lower side of the associated partition, and means for energizing said piles, whereby cach of said piles produces a Peltier eifect to transfer heat from the adjacent lower one of said chambers into the adjacent upper one of said chambers through the associated partition, so as to produce cascaded heat flow upwardly through the chambers in said tier, said piles including progressively increasing numbers of thermocouples upwardly in said tier, so that the temperatures in the chambers are progressively lower than the ambient temperature downwardly in said tier.

2. In a refrigerator, an upstanding hollow heat-insulating cabinet having an open front, an upstanding heat-insulating front door cooperating with the open front of said cabinet, a plurality of substantially horizontally disposed partitions arranged in said cabinet in substantially vertically spaced-apart relation and dening therein a plurality of chambers arranged in a tier and accessible through the open front of said cabinet with said front door in its open position, a plurality of thermo-electric piles respectively arranged in said partitions, each of said piles including a plurality of thermocouples each provided with a hot junction and a cold junction, the hot junctions of the thermocouples in each of said piles being arranged on the upper side of the associated partition and the cold junctions of the thermocouples in each of said piles being arranged on the lower side of the associated partition, and means for energizing said piles, whereby eachy of said piles produces a Peltier eiect to transfer heat from the adjacent lower one of said chambers into the adjacent upper one of said chambers through the associated partition, so as to produce cascaded heat ow upwardly through the chambers in said tier, said piles including progressively increasing number of thermocouples upwardly in said tier, so that the temperatures in the chambers are progressively lower than the ambient temperature downwardly in said tier.

3. In a refrigerator, upstanding hollow heat-insulating cabinet structure having an open top, a top wall closing the open top of said cabinet structure, a partition wall arranged in said cabinet structure and dividing the same into upper and lower chambers, a rst thermo-electric pile arranged in said partition wall and including a plurality of thermocouples each including a cold junction disposed on the lower side of said partition wall in heatexchange relation with said lower chamber and a hot junction disposed on the upper side of said partition wall in heat-exchange relation with said upper chamber, a second thermo-electric pile arranged in said top wall and includnig a plurality of thermocouples each including a cold junction disposed on the lower side of said top wall in heat-exchange relation with said upper chamber and a hot junction disposed on the upper side of said top Wall in heat-exchange relation with the ambient air, and means for energizing said piles, whereby each of said piles produces a Peltier effect, said rst pile transferring heat from said lower chamber into said upper chamber through said partition wall and said second pile transferring heat from said upper chamber into the ambient air through said top wall, said second pile including more thermocouples than said rst pile, so that said upper chamber is cooled to a temperature below the ambient temperature and said lower chamber is cooled to a tertiperature below that of said upper chamber.

4. In an appliance, hollow heat-insulating structure including a wall and dening a chamber, a thermo-electric pile arranged in said wall and including a plurality of thermocouples each including first-type junctions and second-type junctions, the first-type junctions of the thermocouples in said pile being arranged on the inner side of said wall and in heat-exchange relation with the air in said chamber and the second-type junctions of the thermocouples in said pile being arranged on the outer side of said wall and in heat-exchange relation with the air outside of said chamber, means for energizing said pile so that a Peltier effect is produced thereby with the result that heat is transferred in a predetermined direction between the air in said chamber and the air outside of said chamber and through said wall, means including a first screen disposed adjacent to the inner side of said Wall and covering the first-type junctions of the thermocouples in said pile for preventing accidental short-circuiting therebetween, and means.` including a second screen disposed adjacent to the outer side of said wall and covering the second-type junctions of the thermocouples in said pile for preventing accidental short-circuiting therebetween.

5. In an appliance, hollow heat-insulating structure including a wall and dening a chamber, a thermo-electric pile arranged in said Wall and including a plurality of thermocouples each including first-type junctions and second-type junctions, the first-type junctions of the thermocouples in said pile being arranged on the inner side of said wall and in heat-exchange relation with the air in said chamber and the second-type junctions of the thermocouples in said pile being arranged on the outer side of said wall and in heat-exchange relation with the air outside of said chamber, apparatus selectively operative to produce a variable D.C. voltage, means connecting said apparatus to said pile so that a Peltier eifect is produced thereby with the result that heat is transferred in a predetermined direction between the air in said chamber and the air outside of said chamber and through said wall, a temperature-sensing device responsive to the temperature of the air in said chamber, and means governed by said device for selectively controlling the operation of said apparatus so as selectively to establish the voltage produced thereby.

6. In an appliance, hollow heat-insulating structure including a wall and defining a chamber, a thermoelectric pile arranged in said wall and including a plurality of thermocouples each including first-type junctions and second-type junctions, the first-type junctions of the thermocouples in said pile being arranged on the inner side of said wall and in heat-exchange relation with the air in said chamber and the second-type junctions of the thermocouples in said pile being arranged on the outer side of said wall and in heat-exchange relation with the air outside of said chamber, apparatus selectively operative to produce a variable D.-C. voltage, means including a reversing switch for selectively connecting said apparatus to said pile and for selectively establishing the polarity of said connection, so that one polarity of said connection causes said pile to produce a Peltier effect with the result that heat is transferred through said wall from the air n said chamber into the air outside of said chamber and so that the other polarity of said connection causes said pile to produce a Peltier eect with the result that heat is transferred through said wall from the air outside of `said chamber into the 11 plate having a row of holes therethrough that are arranged in substantially equally spaced-apart relation, a plurality of lirst-type elements arranged in odd ones of said holes, a plurality of second-type elements arranged in even ones of said holes, a plurality of substantially identical conductors each including a bridging strap and a heat-exchange fin carried thereby, said conductors being arranged in two groups respectively disposed on opposite sides of said plate, the straps of said conductors arranged on one side of said plate respectively connecting together the ends of adjacent ones of said elements to form first-type thermocouple junctions, the straps of said conductors arranged on the other side of said plate respectively connecting together the ends of adjacent ones of said elements to form second-type thermocouple junctions, whereby all of said elements and all of said conductors are connected in series circuit relation, the fins carried by said two groups of conductors respectively projecting outwardly from the opposite sides of said plate, apparatus selectively operative to produce a variable D.C. voltage, means for connecting said apparatus to said series circuit so that a D.C. current is conducted therethrough causing a Peltier elect with the result that heat is transferred from one group of the fins disposed on one side of said plate to the other group of the fins disposed on the other side of said plate and through said elements in said plate so that the one group of the tins is cooled and the other group of the fins is heated, and means for selectively controlling the operation of said apparatus so as to establish the voltage produced thereby in order to establish the rate of heat transfer from the one group of the fins to the other group of the tins.

8. The thermoeelectric pile set forth in claim 7, wherein said control means includes a temperature-responsive device that is governed by the temperature of a predetermined group of the tins.

9. The thermo-electric pile set forth in claim 7, wherein said control means includes a manually presettable device.

10. The thermo-electric pile set forth in claim 7, wherein said control means includes a control device and a magnetic amplifier governed by said control device for controlling said apparatus.

l1. The thermo-electric pile set forth in claim 7, wherein said first-type elements comprise N-type semiconductor elements, and said second-type elements comprise P-type semi-conductor elements.

12. The thermo-electric pile set forth in claim 7, wherein each of said first-type elements is formed essentially of Bi2Te3 containing a small controlled amount of a donor impurity and each of said second-type elements is formed essentially of Bi2Te3 containing a small controlled amount of an acceptor impurity.

13. The thermo-electric pile set forth in claim 7, wherein said plate is formed essentially of a synthetic organic resin.

14. A thermo-electric pile comprising a plate formed of heat-insulating and electrical-insulating material, said,

plate having a row of holes therethrough that are arranged in substantially equally spaced-apart relation, a plurality of rst-type elements arranged in odd ones of said holes, a plurality of second-type elements arranged in even ones of said holes, a plurality of substantially identical conductors each including a bridging strap and a heat-exchange iin carried thereby, said conductors being arranged in two groups respectively disposed on opposite sides of said plate. the straps of said conductors arranged on one side of said plate respectively connecting together the ends of adjacent ones of said elements and to form first-type thermocouple junctions, the straps of said conductors arranged on the other side of said plate respectively connecting together the ends of adjacent ones of said elements to form second-type thermocouple junctions, whereby all of said elements and all of said conductors are connected in series circuit relation, the fins carried by said two groups of conductors respectively projecting outwardly from the opposite sides of said plate, a source of D.C. current supply, and means for selectively connecting said supply source with either polarity thereof to said series circuit causing corresponding Peltier effects with the result that with one polarity heat is transferred from one group of the lins disposed on one side of said plate to the other group of the tins disposed on the othere side of said plate and through said elements in said plate and with the result that with the' other polarity heat is transferred from the other group of the tins to the one group of the fins and through said elements in said plate.

References Cited in the le of this patent UNITED STATES PATENTS Notice of Adverse Decision in Interference In Interference No. 92,933 involving Patent No. 2,986,009, J. J. Gaysowskn Thermo-electric refrigerators, final judgment adverse to the patentee was rendered. June 3, 1964, as to claims 5 and 6.

[Oyoz'al Gazette August 25, 1.964.]

Notice of Adverse Decision in Interference In Interference N o. 92,933 involving Patent N o. 2,986,009, J. J. Gaysowskn Thermo-electric refrigerators, nal judgment adverse to the patentee was rendered June 3, 1964, as to claims 5 and 6.

[cal Gazette August 25, 1964.] 

